1. Field of the Invention
This invention relates to a slide fastener provided with metallic coupling elements onto which electro-chemical surface treatment such as anodized film forming, electrolytic plating, electrodeposition coating or the like is carried out.
2. Prior Art
In the slide fastener with a plurality of metallic coupling elements attached at regular intervals along the longitudinal edge of one side of the fastener tape, when electro-chemical surface treatment such as anodized film forming, electrolytic plating, electrodeposition coating or the like is carried out for each metallic coupling element, it is required to apply an electric current to each of the metallic coupling element. Therefore, electric conductors are arranged along the longitudinal edge of one side of the fastener tape provided with the coupling elements.
The prior art exemplifying the slide fastener having the electric conductors arranged along its edge are disclosed, for example, in Japanese Utility Model Publication No. S59-27136 and in the U.S. Pat. No. 2264324. According to the disclosed structure, the electric conductors are attached on and along the core cord of the fastener tape or wound helically around the core cord, so that they are protruded on the surface of the core cord.
In die-casting of metallic coupling elements, the fastener tape is sandwiched between upper mad lower metal molds to cast plural coupling elements at regular intervals therealong. Then, concave grooves are formed between cavities of the upper and lower metal molds for fastener coupling elements to fit the longitudinal edge of one side of the fastener tape therein. When the longitudinal edge of one side of the fastener tape is inserted into the concave grooves, electric conductors protruded on the front surface must cut into the core cord without protruding from the concave grooves and the upper and lower metal molds must be firmly contacted with each other in clamping thereof.
However, with the prior art examples, the protruded electric conductors might be cut off by being not completely received in the concave grooves and sandwiched between the edges of the concave grooves of the upper and lower metal molds. Therefore, it was impossible to carry out the successive electrolytic plating.
In the metallic coupling elements of pressed products, a plurality of fastener coupling elements are planted at regular intervals by caulking their legs while the electric conductors are attached along the longitudinal edge of the cord side of the fastener tape. Unlike the above-mentioned cast-molding, this process has higher probability that the electric conductors protruded on the fastener tape are cut off because the caulking force is necessarily applied to all coupling elements exerting the pressure upon the cord. Therefore, poor current application may be caused more often than the casting process.